Problem

Session mirror logs grow unbounded and accumulate noise, especially from early versions before the cursor-tracking ANSI parser was implemented.

Current state:

• 111,423 lines across 10 session mirror files
• Largest single session: 49,607 lines (1.5MB)
• Current session: 10,518 lines (550KB)
• Much of the older content is garbage — raw ANSI artifacts, spinner frames, duplicated lines from before mirror_strip_ansi() was implemented

The session mirror tab (tail -f) becomes slow and hard to navigate in long sessions. The log files on disk accumulate without cleanup.

Proposed Solutions

1. Log Rotation (Within a Session)

• Cap mirror log at N lines (e.g., 5,000) or N MB (e.g., 2MB)
• When the cap is hit, rotate: rename current to session-{ts}.1.log, start fresh
• Or truncate the top (oldest content) and keep the bottom (most recent)
• tail -f handles rotation gracefully with tail -F (follows file name, not inode)

2. Session Startup Cleanup

• On launch, archive or delete session mirror logs older than N days
• Or compress old logs (gzip)
• Add a --keep-days <N> flag (default: 7)

3. Smarter Filtering (Reduce Volume)

• The cursor-tracking parser already filters a lot, but long sessions still produce thousands of lines
• Consider rate-limiting mirror writes (e.g., flush every 500ms instead of every PTY read)
• Deduplicate more aggressively — current dedup window is 32 lines, could be larger
• Skip writing during heavy TUI repaints (detect rapid cursor-home sequences)

4. Summary Mode

• Instead of raw transcript, periodically write a summary line:
  [09:15:23] Working on: updating CLAUDE.md files (5 tool calls in last 2 min)
• Would require tracking tool call patterns, but dramatically reduces volume

Immediate Quick Win

Delete/archive the pre-parser garbage logs. Everything before the cursor-tracking parser was added is mostly unreadable noise.

Acceptance Criteria

• Session mirrors stay under a reasonable size (configurable)
• Old logs are cleaned up automatically
• tail -f remains responsive in long sessions
• No data loss for recent session content